A classical dynamics model is used to investigate nuclear motion in solids due to bombardment by energetic atoms and ions. Of interest are the mechanisms of ejection and cluster formation both of elemental species such as Ni//n and Ar//n and molecular species where we have predicted intact ejection of benzene-C//6H//6, pyridine-C//5H//5N, napthalene-C//1//0H//8, biphenyl-C//1//2H//1//0 and coronene-C//2//4H//1//2. The results presented here show that the energy distributions of the parent molecular species, e. g. benzene, are narrower than those of atomic species, even though the ejection processes in both cases arise from energetic nuclear collisions. The bonding geometry also influences the ejection yield and angular distribution. The specific case of pi -bonded and sigma -bonded pyridine on a metal surface is discussed with comparisons between the calculated results and experimental data.